Third rail contact shoe



June 30, 1959 R. H. SIERK THIRD RAIL CONTACT SHOE 2 Sheets-Sheet 1 Filed March 9, 1954 INVENTOR. kflfa gmwud 9f .June 30, 1959 R. H. SIERK 2,892,904

' THIRD RAIL CONTACT SHOE Filed March 9, 1954 2 Sheets-Sheet 2 United States Patent O fifice 2,832,904 Patented June 30, 1959 THIRD RAIL CONTACT SHOE Raymond H. Sierk, Whitestone, N.Y. Application March 9, 1954, Serial No. 415,011

4 Claims. (Cl. 191-,49)

This invention relates to third rail contact means by which current is taken from a third rail by a moving car of an electrical railway. The present invention constitutes an improvement of the type of shoe disclosed by my U.S. Letters Patent No. 2,161,100, issued June 6, 1939, for Third RailContact Shoe.

A primary object of the present invention is to devise a novel and more effective connection between the fulcrum member and wear pad of this type of shoe.

A more specific object of the invention is to devise a novel shoe wherein one' ormore compression spring units may be utilized to maintain the contact areas of the fulcrum member and pad in tight engagement to minimize arcing of electrical current between these parts.

Another object of the invention is to prevent substantial flow of electrical current through the spring units.

A further object of the invention is to devise a novel shunt; compressed against the fulcrum member and Wear pad by the compression spring unit.

Still another object of the invention is to equalize pressure of the spring units against conventional machined bearing areas of the wear pad at opposite sides of its longitudinalvertical center plane.

Yet another object of the invention is to provide a secondary contact surface on the wear pad spaced from its primary contact surface which engages the third rail.

The foregoing and other objects and advantages of the invention will become apparent from a consideration of the following specification and the accompanying drawings, wherein:

Figure 1 is a top plan view of: a novel third rail contact shoe embodying the invention;

Figure 2 is a sectional view on the line 2-2 of Figure 1; I V

Figure 3 is a sectional view' on the line 3--3- of Figure 2;

Figure 4'- is a sectional view similar to Figure 2 but illustrating a modification of the invention;

Figures Sand 6 are respectively a side elevational view and a top plan view of the spring package utilized in the modification of Figure 4;

Figure 7 illustrates a further modification of the spring package, and

Figure 8 is a. sectional view taken substantially along inboard side thereof by a central rib 6, said flange forming, a means of abutment as at 8 against a convenient portion of an associated car truck (not shown) to limit clockwise rotation of the fulcrum as viewed in Figure 2.

The fulcrum member may be pivotally mounted as at 10 on a shaft (not shown) extending through horizontally aligned openings 12 of the fulcrum member, said shaft being mounted in any suitable manner upon the car truck. Adjacent the pivot point 10 and at one side of thefulcrum member is provided a tapped opening 14 for the reception of an associated shunt terminal bolt (not shown).

At the opposite end of the fulcrum member 2 and in longitudinal alignment therewith, as viewed in Figures 1 and 2, there is an electrically conductive wear pad generally designated 16 in the form of a Hat plate like structure comprising longitudinal ribs 18, transverse ribs 20, and a central opening 22 to accommodate a voltage plug (not shown). The inboard end of the wear pad 16 comprises a tongue 24 having a transverse horizontally disposed keyway 26 of novel form, as hereinafter described. The keyway 26 receives a conventional key 28, and the tongue 24 is accommodated in a longitudinally extending slot 30 formed in the bottom of the fulcrum member 2 and partly defined by a bridge 32 which may have a downwardly facing abutment surface 33 on the underside thereof.

Inboardly of the bridge 32 the fulcrum member 2 is formed with a central opening or aperture 34 accommodating a bridge 36 which partly defines the before mentioned keyway 26. The opening 34 is formed in the top of the fulcrum member 2 and communicates with the slot 30. The ends of the key 28 are positioned on upwardly facing key seats 38 of the fulcrum member 2 at opposite sides of the opening 34 and defining the lateral margins thereof. The key seats 38 are provided with lateral ribs 40 engageable with the ends of the key 28 to revent accidental loss thereof in service.

It may also be noted, as best seen in Figure 3, that the portion of tongue 24 in the opening 34 is provided with an arcuate secondary contact surface 41 spaced from the primary contact surface 43 and projecting from opening 34 below the fulcrum member 2, to engage the associated third rail (not shown) under certain conditions.

The inboard or free end of the tongue 24 is upturned as at 42 to define an upwardly facing spring seat 44 aligned with a downwardly facing spring seat 46 of the fulcrum member 2, said seat 46 being defined at its inboard edge by a shoulder 43 on the underside of the fulcrum member 2. One or more compression spring units generally designated 50 are compressed by and between the spring seats 44 and 46, each of said units preferably comprising outer and inner coils 52 and 54, respectively. In the illustrated embodiment of the invention, a pair of compression spring units 50 are utilized to afford maximum spring pressure within the available space, said units being disposed at opposite sides of the longitudinalverth cal center plane of the novel shoe.

To insure equalized pressure of the spring units 50 against a conventional shunt 55 along spaced machined bearing areas 56 of the wear pad 16 at opposite sides of said center plane, the underside of the bridge 36 which bears against the key 28' may comprise a downwardly facing surface 57 which is substantially convex in transverse vertical cross section, as shown in Figure 3, and is concave in longitudinal vertical cross section, as shown in Figure 2, to afford substantial line contact between the key 28 and bridge 36 along the longitudinal vertical center plane of the shoe, whereby pressure of the spring units 50 is equalized against the spaced machined bearing areas 56 of the wear pad 16 to minimize arcing at these areas. In this connection, it may be noted that the shunt 55 is compressed by the bearing areas 56 against the downwardly facing surface 33 of the bridge 32 which partly defines the slot 30 in the fulcrum member 2, as best shown in Figure 2.

Another important feature of the invention resides in the provision of novel shunt means to prevent substantial flow of electrical current through the spring units 50, where, as in the illustrated embodiment, they are electrically conductive. Such shunt means comprise a generally U-shaped shunt strap 58 of soft copper or other suitable material having a much higher coefficient of electrical conduction than that of the spring units 50. The strap 58 confines the ends of the spring units 50 so that these units do not bear directly against the fulcrum 2 and wear pad 16.

Thus momentary lowering of spring pressure against the bearing areas 56, as for example when the wear pad 16 drops off the third rail (not shown) does not cause arcing of the current through the spring units 50, which arcing might tend to soften the spring units and lower their capacity.

This novel arrangement also affords equalized pressure of the strap 58 against the spring seats 44 and 46 of the wear pad 16 and fulcrum member 2, respectively, due to the manner in which the ends of the spring units 50 which react against the wear pad and fulcrum member are seated against the strap 58 and react through the strap against the spring seats 44 and 46. In other words, the strap 58 affords a flexible container for the spring units 50, so that they exert equalized pressure against the fulcrum member 2 and wear pad 16,

Figures 4 to 6 show a modification of the novel device and parts corresponding to those of Figures 1 to 3 are identified by corresponding numerals.

In the modification of Figures 4 to 6 the inboard end of the wear pad 16 is provided with an upturned lug or tail 60 received within a recess 62 of the fulcrum member 2, to positively prevent accidental displacement of the spring means therein and to prevent foreign matter from entering the recess 62.

Said spring means and the recess 62 comprise the before mentioned compression springs 52 and 54. A copper wire 64 is threaded through each spring 54, the ends of the wire being soldered or otherwise secured to the shunt strap 58 for the purpose of holding springs 52 and 54 in a package or unit with the shunt strap 58 prior to assembly of these parts with the fulcrum member 2 and wear pad 16, as illustrated in Figure 4. This unit or package is shown in detail in Figures 5 and 6 prior to assembly, and it will be noted that on these figures the wires 64 hold the strap 58 snugly against the springs 52 and 54. Figure 4 shows this package in assembled relationship with the fulcrum member 2 and wear pad 16 under which conditions the springs 52 and 54 are compressed.

If desired, the springs 52 and 54 may be held under slight precompression by the wires 64 prior to assembly of the spring package with the fulcrum member and wear pad.

Another feature of the modification resides in the manner in which the lower surface of the wear pad 16 is relieved inboardly of its surface 43 so that the lower surfaces of pad 16 and fulcrum member 2 are flush with respect to each other at the point indicated by numeral 66. The outline of the pad shown in Figures 1 to 3 is partly shown in phantom lines in Figure 4 in order to clearly illustrate the improved clearance conditions of Figure 4, as well as the manner in which the upturned tail projects into the fulcrum member recess 62.

The modification of Figure 4 also utilizes a round pin indicated at 28a, although it will be understood that, if desired, a fiat sided pin such as that shown at 28 in Figure 2 may be utilized.

Referring now to Figure 7, a modified spring package is illustrated. In this modification the springs 52 and 54 are maintained in assembly with the shunt trap by a copper ribbon 70 sleeved through each spring 54 and extending through slots in the shunt strap 58. The upper and lower ends of each ribbon are flanged as at 72 and 74 and are secured to the shunt strap 58 in any desired manner as, for example, by soldering. If desired, the

flanges 72 and 74 may be sufficiently short to fit within the inner diameter of the spring 54 within recesses in the shunt strap 58 which recesses may be conveniently formed by denting the shunt strap at these points.

I claim:

1. A third rail contact shoe comprising: an electrically conductive substantially horizontally disposed fulcrum member having means at one end thereof for Ipivotal connection on a substantially horizontal axis to an associated vehicle, said member having an aperture extending substantially vertically therethrough adjacent the other end thereof, said member having a slot extending from said other end to said aperture and being at least partly defined by a top wall of said member; an electrically conductive wear pad extending substantially coplanar with said member and having spaced contacts with said top wall laterally of said slot, said wear pad extending through said slot and having a portion extending through said aperture and vertically above the top surface of the side walls of said aperture, said portion having an opening above said top surface extending transversely of said member and pad; hinge pin means received through said opening and projecting beyond both ends thereof, said pin means having surfaces bearing against spaced upwardly facing surfaces of said member and against a downwardly facing surface of said portion, said downwardly facing surface being arcuately concave in longitudinal vertical cross section and arcuately convex in transverse vertical cross section, a tongue on said wear pad extending toward said pivotal connection and positioned below and spaced from said member; resilient means between said member and said tongue urging said member and said pad together at said contact and bearing surfaces; and flexible shunt means received between said resilient means and said member and pad, respectively.

2. A contact shoe comprising an electrically conductive generally horizontally disposed fulcrum member having means at one end thereof for pivotal mounting on a substantially horizontal axis, said member having a substantially vertical aperture therethrough adjacent the other pin means received through said opening and having sur faces bearing against spaced upwardly facing surfaces of said member and against a downwardly facing surface of said pad, said downwardly facing surface being arculately convex in transverse vertical cross section; a tongue on said wear pad extending beyond said opening on the side thereof opposite said top wall and positioned below and spaced from said member; and resilient means between said member and said tongue urging said member and pad together at said contact and bearing surfaces.

3. A third rail contact shoe comprising: a generally horizontally disposed electrically conductive fulcrum member having an aperture intersecting the top and bottom surfaces thereof intermediate its ends; a generally horizontally disposed electrically conductive wear pad lying partly beneath said member and said aperture and in contact with said bottom surface, said wear pad having a portion extending through said aperture to a point vertically above said top wall, said portion having an opening extending transversely of said member and at least partly disposed above said top surface; pivot pin means received through said opening and having surfaces bearing against spaced upwardly facing surfaces of said member and against a downwardly facing surface of said wear pad, said downwardly facing surface being arcuately convex in transverse vertical cross section; a tongue on said wear pad below and spaced from said member on the side of said aperture opposite the point of contact of said bottom surface and said wear pad, and resilient means between said member and said tongue urging said member and pad together at said contact and bearing surfaces.

4. A contact shoe comprising a generally horizontally disposed electrically conductive fulcrum member having an aperture intersecting the top and bottom surfaces thereof generally intermediate its ends; a generally horizontally disposed electrically conductive wear pad lying partly beneath said member and said aperture and in contact with said bottom surface, said wear pad having a portion extending through said aperture to a point vertically above said top surface, said portion above said top surface presently a downwardly facing surface; pivot pin means disposed transversely of said member and in contact with said downwardly facing surface and with spaced areas of said top surface on either side of said downwardly facing surface, said downwardly facing surface being arcuately convex in transverse vertical cross section; and resilient means urging said member and pad together at said contact and bearing surfaces.

References Cited in the file of this patent UNITED STATES PATENTS 1,370,018 Hipple Mar. 1, 1921 1,746,650 Harrington Feb. 11, 1930 1,846,263 Kull Feb. 23, 1932 1,893,383 Way Jan. 3, 1933 1,950,486 Frank Mar. 13, 1934 2,161,100 Sierk June 6, 1939 2,251,529 Sterling Aug. 5, 1941 2,637,088 Foster May 5, 1953 2,687,295 Tucker Aug. 24, 1954 

